The law requires abortion providers to have admitting privileges at nearby hospitals. That means a provider could automatically send a patient to a hospital, if needed.

Planned Parenthood and Affiliated Medical Services immediately filed a lawsuit challenging that requirement. A federal judge put that part of the law on hold while the legal challenge was worked out.

The law also requires a woman seeking abortion to get an ultrasound. That requirement is in effect.

The trial began Tuesday morning in Madison. Attorneys for abortion providers want to convince a federal judge that the law is unconstitutional.

"I think the politicians in the Wisconsin Legislature who were pushing this really didn't care about providing health care to women in need of these services," said Chris Ahmuty, the executive director of the ACLU of Wisconsin.

State Rep. Andre Jacque, R-De Pere, was a co-sponsor of the bill when it went through the state legislature. He says the law protects women.

"It's just about really shining some light on an industry that I don't think is particularly helpful to women in terms of their evasion of accountability for patient safety," said Jacque.

Planned Parenthood had said the law would force its abortion clinic in Grand Chute to close because its providers lacked admitting privileges. Providers there have since gained privileges.

In court documents, Planned Parenthood argues: "It is uncertain whether... physicians who recently obtained admitting privileges at an Appleton hospital will ultimately be able to maintain them..."

Jacque has another view.

"Again it begs the question, who is it that would not be able to get hospital admitting privileges?" he asked.

Opponents say the law makes it more difficult for providers to remain open.

"Politicians will achieve their apparent goal of harming women," said Ahmuty.

Proceedings in federal court are expected to last until at least Friday. Any decision would likely be appealed. The case could ultimately be decided in the U.S. Supreme Court.

Affiliated Medical Services in Milwaukee is also part of the lawsuit. Providers there do not have admitting privileges yet. That clinic would no longer be able to perform abortions if the law is upheld.